1. Field of the Disclosure
The disclosure relates to a control method for a data storage system, and more particular to the control method of data storage system when the expander is restarted.
2. Description of the Related Art
Compared to data storage devices of the past, data storage devices nowadays have the advantages of enhanced data integration, enhanced fault tolerance and larger processing capacity or storage capacity. A Redundant Array of Independent Disks (RAID) combines a plurality of cheaper disks so that its efficiency is better than a disk which is more expensive and has a larger storage capacity. As shown in FIG. 1, a disk system 120 includes at least one expander 121 and a plurality of disk groups 122 to 126 and a server system 110 includes a server 111 and a RAID control device 112. The expander 121 is coupled to the disk groups 122 to 126 and the RAID control device 112.
The disk system 120 and the expander 121 need to be restarted under the watchdog timeout warning mechanism of the expander 121 when unpredictable factors cause the disk system 120 to fail to operate normally. When the expander 121 is restarted, taking into consideration the instantaneous current, the expander 121 needs to supply power to the disk groups 122 to 126 of the disk system 120 sequentially and individually to avoid power to the disk system 120 being tripped off. It leads to more than one minute spent waiting for all the disk groups 122 to 126 of the disk system 120 are completely ready.
However, the time spent on the error-handling mechanism of the RAID control device 112 cannot exceed one minute when the disk system 120 has failed to operate normally because of the unpredictable factors. If the time spent waiting for all the disk groups 122 to 126 be completely ready exceeds the time spent on the error-handling mechanism of the RAID control device 112, the RAID control device 112 would determine that the unready disk groups are damaged. That causes damage to user data (for example, Facebook, Rackspace, Google . . . etc.). Therefore the present disclosure provides a disk system and a control method thereof to solve the above problem.